Electronically-controlled mechanically-damped off-resonant light beam scanning mechanism and code symbol readers employing the same

ABSTRACT

Disclosed is laser beam scanning apparatus in the form of an electronically-controlled mechanically-damped off-resonant laser beam scanning mechanism. The scanning mechanism comprises an etched scanning element having a small flexible gap region of closely-controlled dimensions disposed between an anchored base portion and a laser beam deflecting portion The light beam deflecting portion supports a permanent magnet and a light beam deflecting element (e.g., mirror or hologram). A reversible magnetic force field producing device (e.g., an electromagnet) is placed in close proximity with the permanent magnet so that it may be forcibly driven into oscillation in response to electrical current flowing through the electromagnet. The resonant frequency of oscillation of the laser beam deflecting portion relative to the anchored base portion is determined by the closely controlled dimensions of the flexible gap region set during manufacture. The steady-state frequency of oscillation of the laser beam deflecting portion is determined by the frequency of polarity reversal of the electromagnet, which is electronically controlled by the polarity of electrical current supplied thereto. In the illustrative embodiments, the forcing frequency of the electromagnet is selected to be at least ten percent off (i.e., greater or less than) the natural resonant frequency of the laser beam deflecting portion of the scanning element. The steady-state frequency of oscillation can be set at the time of manufacture to be any one of a very large range of values (e.g., 25-127 Hz) for use in both low-speed and high-speed laser scanning systems.

[0001] Ser. No. 08/561,479 filed Nov. 20, 1995; copending applicationSer. No. 08/278,109 filed Nov. 24, 1995; copending application Ser. No.08/489,305 filed Jun. 9, 1995; copending Ser. No. 08/476,069 filed Jun.7, 1995; copending application Ser. No. 08/584,135 filed Jan. 11, 1996which is a continuation of copending application Ser. No. 08/651,951filed May 21, 1996 which is a continuation of copending application Ser.No. 08/489,305 filed Jun. 9, 1995 which is a continuation of applicationSer. No. 07/821,917 filed Jan. 16, 1992, now abandoned, which is acontinuation-in-part of application Ser. No. 07/583,421 filed Sep. 17,1990, now U.S. Pat. No. 5,260,553, and application Ser. No. 07/580,740filed Sep. 11, 1990, now abandoned. Each said patent application isassigned to and commonly owned by Metrologic Instruments, Inc. ofBlackwood, N.J., and is incorporated herein by reference in itsentirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of Invention

[0003] The present invention relates to laser scanning systems and moreparticularly, to electronically-controlled damped off-resonantmechanisms for reliably scanning laser beams during bar code symbolreading operations and the like.

[0004] 2. Brief Description of the Prior Art

[0005] Laser scanning bar code symbol scanners are widely used to readbar code symbols on products and packages for identification purposes.Many different techniques exist for scanning laser beams across objects.

[0006] One commonly used beam scanning technique involves driving aresonant element bearing a mirror into oscillatory motion within aplane, while a laser beam is directed incident the mirror surface. Asthe resonant element oscillates, so too does the mirror, causing theincident laser beam to be scanned across a scanning field ofsubstantially planar extent, as well as a bar code symbol disposedtherewithin. In general, laser light reflected from the scanned bar codesymbol is collected and detected to produce an electrical signalrepresentative of the scanned symbol. Ultimately, the electrical signalis processed in order to decode the scanned symbol and produce symbolcharacter data representative of the decoded symbol.

[0007] In U.S. Pat. Nos. 5,168,149, 5,280,165, 5,374,148 and 5,581,067,several different scanning mechanisms are disclosed, in which stripsmade of Mylar™ or Kapton™ plastic material are used to realize resonantscanning elements. While such prior art scanning elements are durable,they are not without their shortcomings and drawbacks.

[0008] Such prior art laser scanning mechanisms are generally massiveand large in comparison to size of scanning mirror supported thereby.Prior art laser scanning mechanisms are generally difficult to produce,expensive to manufacture, difficult to precisely tune, and typicallyrequire an anti-shock mechanism to protect the scanning element fromdamage when dropped. Consequently, there are numerous applications wheresuch limitations prevent such prior art scanning mechanisms from beingused in a commercially feasible manner.

[0009] Addressing the shortcomings and drawbacks associated with theabove-described scanning mechanism, Applicants hereof have attempted toconstruct a laser beam scanning mechanism, in which a thin strip ofKapton™ film, anchored at its base end and supporting a miniature mirrorand a ferrite magnetic on its free end, is driven in an off-resonantmode of operation in order to scan a laser beam incident the mirror.While laboring long and hard, Applicants have been unable toconsistently manufacture in large volume and at low cost, a laser beamscanning mechanism based on such prior art design principles, withoutseriously sacrificing the operation and performance thereof.

[0010] Consequently, hitherto, Metrologic's ScanQuest® Laser ScanningEngine (Models 4110 and 4120), in which the above-described scanningmechanism was employed, could not be manufactured in high volume or atlow cost.

[0011] Therefore, there is a great need in the art for an improved laserscanning mechanism which avoids the shortcomings and drawbacks of priorart laser beam scanning apparatus and methodologies.

OBJECTIVES AND SUMMARY OF THE INVENTION

[0012] Accordingly, it is a primary object of the present invention toprovide improved laser beam scanning apparatus that avoids theshortcomings and drawbacks of prior art technologies.

[0013] A further object of the present invention is to provide suchlaser beam scanning apparatus in the form of anelectronically-controlled mechanically-damped off-resonant laser beamscanning mechanism comprising an etched scanning element having a smallflexible gap region of closely-controlled dimensions disposed between ananchored base portion and a laser beam deflecting portion.

[0014] Another object of the present invention is to provide such alaser beam scanning mechanism, in which the resonant frequency ofoscillation of the laser beam deflecting portion relative to theanchored base portion is determined by the closely controlled dimensionsof the flexible gap region set during manufacture.

[0015] A further object of the present invention is to provide such alaser beam scanning mechanism, in which the resonant frequency ofoscillation of the scanning element is tuned by adjusting the thicknessand width of the flexible gap region.

[0016] Another object of the present invention is to provide such alaser beam scanning mechanism, in which the physical dimensions of theflexible gap region are closely controlled by using chemical-etchingtechniques during manufacture.

[0017] Another object of the present invention is to provide such alaser beam scanning mechanism, in which the etched scanning element ismanufactured by chemically etching a double-sided copper clad sheetconsisting of a polyamide base material laminated between ultra-thincopper sheets.

[0018] Another object of the present invention is to provide such alaser beam scanning mechanism, in which a permanent magnet is mounted onthe rear surface of the laser beam deflecting portion, and a laser beamdeflecting element is mounted on the front surface of the laser beamdeflecting portion.

[0019] Another object of the present invention is to provide such alaser beam scanning mechanism, in which the base portion is securelyfixed to an optical bench and the laser beam deflecting portion isforced to oscillate substantially away from the natural resonantfrequency of the scanning element, by a reversible electromagnetdisposed in close proximity to permanent magnetic mounted to the rearsurface of the laser beam deflecting portion.

[0020] Another object of the present invention is to provide such alaser beam scanning mechanism, in which the natural harmonic (i.e.,resonant) frequency of the laser beam deflecting portion about theanchored base portion is mechanically-damped by adding a thin layer offlexible rubber material to the gap region of the scanning elementduring manufacture, and the laser beam deflecting portion is forciblydriven by a reversible electromagnet operated at a forcing (i.e.,driving) frequency tuned substantially away (i.e., off) from the naturalresonant frequency of the laser beam deflecting portion.

[0021] Another object of the present invention is to provide such alaser beam scanning mechanism, in which the steady-state frequency ofoscillation of the laser beam deflecting portion is determined by thefrequency of polarity reversal of the electromagnet, which iselectronically controlled by the polarity of electrical current suppliedto the input terminals of the magnet coil of the reversibleelectromagnet.

[0022] Another object of the present invention is to provide such alaser beam scanning mechanism, in which the driving or forcing frequencyof the electromagnet is selected to be at least ten percent off (i.e.,greater or less than) the natural resonant frequency of the laser beamdeflecting portion.

[0023] Another object of the present invention is to provide such alaser beam scanning mechanism, in which the steady-state (i.e.,controlled) frequency of oscillation of the scanning element can be setat the time of manufacture to be any one of a very large range of values(e.g., 25-125 Hz) for use in both low-speed and high-speed laserscanning systems.

[0024] Another object of the present invention is to provide such alaser beam scanning mechanism having ultra-low power consumption, and alow operating current.

[0025] Another object of the present invention is to provide such alaser beam scanning mechanism, in which the angular sweep of the laserbeam deflecting element is about thirty (i.e., ±15° degrees) measuredwith respect to the point of pivot about the anchored base portion ofthe scanning element of the present invention.

[0026] Another object of the present invention is to provide such alaser beam scanning mechanism, in which the scanning element andelectromagnet are mounted within an ultra-compact housing havingintegrated stops for delimiting the sweep that the scanning element ispermitted to undergo during operation.

[0027] Another object of the present invention is to provide such alaser beam scanning module for use in hand-held, body-wearable, andstationary bar code symbol reading systems having a 1-D laser scanningpattern.

[0028] Another object of the present invention is to provide a 2-D laserscanning module constructed from the assembly of a pair of 1-D laserscanning modules of the present invention.

[0029] Another object of the present invention is to provide a 2-D laserscanning module, in which the 2-D laser scanning pattern producedthereby is electronically-controlled by electronic circuitry used toproduce current drive signals provided to the electromagnetic coils ofthe reversible electromagnets mounted within the laser beam scanningmodules of the present invention.

[0030] Another object of the present invention is to provide a novelmethod for manufacturing scanning elements used in the laser beamscanning mechanisms and modules of the present invention.

[0031] A further object of the present invention is to provide ahand-supportable laser scanning bar code symbol reader employing thelaser beam scanning module of the present invention, in order toSelectively produce either a 1-D or 2-D laser scanning pattern forreading 1-D or 2-D bar code symbols, respectively.

[0032] A further object of the present invention is to provide aportable data (transaction) terminal having the laser beam scanningmodule of the present invention integrated therewith, in order toproduce either a 1-D or 2-D laser scanning pattern by manual selection,or bar code symbol programming, for reading 1-D or 2-D bar code symbols,respectively.

[0033] A further object of the present invention is to provide abody-wearable transaction terminal having the laser beam scanning moduleof the present invention integrated therewith, in order to selectivelyproduce either a 1-D or 2-D laser scanning pattern for reading 1-D or2-D bar code symbols, respectively.

[0034] A further object of the present invention is to provide abody-wearable Internet-based transaction terminal having the laser beamscanning module of the present invention integrated therewith, in orderto read 1-D or 2-D URL-encoded bar code symbols.

[0035] A further object of the present invention is to provide a 2-Dlaser scanning bar code symbol reader, in which a real-time analysis ofthe bar code symbol structure being scanned is used to automatically setthe resolution of the 2-D laser scanning pattern in order to scan 2-Dbar code symbols in an optimal manner.

[0036] These and other objects of the present invention will becomeapparent hereinafter and in the claims To Invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] For a more complete understanding of the present invention, theappended figure drawings should be read in conjunction with thefollowing Detailed Description of the Illustrative Embodiments, inwhich:

[0038]FIG. 1 is a schematic diagram of the laser beam scanning mechanismof the present invention, showing the anchored base portion thereofmounted on a support structure of an optical bench and the laser beamdeflecting portion, extending from the base portion, bearing a lightbeam deflecting element on its front surface and a magnetic element onits rear surface for interaction with an externally generated magneticforce field produced by a miniature electromagnet driven by anelectrical pulse train having a frequency which is controlled by anelectronic signal generation circuit;

[0039]FIG. 1A is a cross-sectional view of the laser beam , scanningmechanism of the present invention, taken along line 1A-1A of FIG. 1;

[0040]FIG. 1B is a cross-sectional view of the resonant scanningmechanism of the present invention, taken along line 1B-1B of FIG. 1;

[0041]FIG. 2 is a perspective view of a chemically-etched sheet ofdouble-sided copper-clad base material used to mass-manufacture thescanning element of the present invention;

[0042]FIG. 2A is a cross-sectional view taken along line 2A-2A of FIG. 2showing a portion of the double-sided copper-clad base material that hasnot been chemically etched;

[0043]FIG. 2B is a cross-sectional view taken along line 2B-2B of FIG. 2showing a portion of the double-sided copper-clad base material that hasbeen chemically etched so as to form seven rows of three scanningelements therefrom;

[0044]FIG. 3 is a schematic diagram of a first illustrative embodimentof a miniature laser scanning engine realized upon an optical benchusing a laser diode, a stationary folding mirror, an electromagneticcoil, and the laser beam scanning mechanism of the present inventionshown in FIG. 1;

[0045]FIG. 3A is a schematic diagram of an electronic circuit forproducing the voltage drive signal applied to the magnetic fieldproducing coil in the scan engine of FIG. 3.

[0046]FIG. 4 is a perspective view of a second illustrative embodimentof a miniature laser beam scanning module realized using anultra-compact plastic housing in which the laser beam scanning mechanismof the present invention shown in FIG. 1 is mounted;

[0047]FIG. 4A is a perspective view of a subcomponent of the scanningmechanism of the second illustrative embodiment which is snap connectedto the housing shown in FIG. 4 and functions to delimit the angularexcursion under which the scanning element hereof is permitted to goduring scanner operation;

[0048]FIG. 5 is a perspective diagram of third illustrative embodimentof the present invention, in which a pair of miniature laser beamscanning modules shown in FIG. 4 are configured on an optical bench toform an ultra-compact laser beam scanning device capable of producingeither a 1-D or 2-D raster-type laser scanning pattern by manuallydepressing an externally-mounted button or switch, or by reading apredetermined bar code symbol encoded to automatically induce aparticular mode of scanner operation;

[0049]FIG. 6 is a partially schematic, partially block diagram ofcircuitry for producing synchronized drive signals for the ultra-compact1-D/2-D laser scanning device shown in FIG. 5, and automatically settingthe resolution of the 2-D laser scanning pattern produced therefrom inresponse to a real-time analysis of scanned 2-D bar code symbols;

[0050]FIG. 7A is a schematic representation of the output clock signalused to synchronize the current drive signal supplied to theelectromagnetic coil of the X-axis laser beam scanning module integratedinto the ultra-compact laser scanning device of FIG. 5;

[0051]FIG. 7B is a schematic representation of the drive current signalsupplied to the electromagnetic coil of the X-axis laser beam scanningmodule of the ultra-compact laser scanning device of FIG. 5;

[0052]FIG. 7C is a schematic representation of the voltage signal usedto drive the electromagnetic coil of the Y-axis laser beam scanningmodule of FIG. 5 when a two-line raster scanning pattern is to beproduced;

[0053]FIG. 7D is a schematic representation of the voltage signal usedto drive the electromagnetic coil of the Y-axis laser beam scanningmodule of FIG. 5 when four-line raster scanning pattern is to beproduced;

[0054]FIG. 7E is a schematic representation of the voltage signal usedto drive the electromagnetic coil of the Y-axis laser beam scanningmodule of FIG. 5 when eight-line raster scanning pattern is to beproduced;

[0055]FIG. 8A1 is a plan view of the 1-D laser scanning pattern producedfrom the graphical representation of a one-dimensional (1-D) laserscanning pattern produced from the laser scanning module shown in FIGS.5 through 7E, integrated within a hand-supportable bar code symbolreader;

[0056]FIG. 8A2 is an elevated side-view of the one-dimensional (1-D)scanning pattern produced from the laser scanning module of the presentinvention shown in FIGS. 5 through 7E, shown integrated within ahand-supportable bar code symbol reader;

[0057]FIG. 8B is an elevated side-view of a two-line raster scanningpattern produced from the laser scanning module of the present inventionshown in FIGS. 5 through 7E, shown integrated within a hand-supportablebar code symbol reader;

[0058]FIG. 8C is an elevated side-view of a four-line raster scanningpattern produced from the laser scanning module of the present inventionshown in FIGS. 5 through 7E, shown integrated within a hand-supportablebar code symbol reader;

[0059]FIG. 8D is an elevated side-view of a eight-line raster scanningpattern produced from the laser scanning module of the present inventionshown in FIGS. 5 through 7E, shown integrated within a hand-supportablebar code symbol reader;

[0060]FIG. 9 is a schematic diagram of the hand-supportable multi-scanpattern generating bar code symbol reader of the present invention shownbeing used in its hands-free (i.e., stand-supported) mode of operation;

[0061]FIG. 9A is a schematic diagram of the hand-supportable multi-scanpattern generating bar code symbol reader of the present invention shownbeing used in its hands-free (i.e., stand-supported) mode of operation;

[0062]FIG. 10 is a perspective view of a portable Internet-based datatransaction terminal according to the present invention, in which thelaser beam scanning module of FIGS. 5 and 6 is integrated therewith forscanning 1-D and 2-D bar code symbols; and

[0063]FIG. 11 is a perspective view of a body-wearable Internet-baseddata transaction terminal according to the present invention, in whichthe laser beam scanning module of FIGS. 5 and 6 is integrated therewithfor scanning 1-D and 2-D bar code symbols.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS OF THE PRESENTINVENTION

[0064] The illustrative embodiments of the present invention will bedescribed with reference to the figure drawings wherein like elementsand structures are indicated by like reference numbers.

[0065] Overview of the Laser Beam Scanning Mechanism of the PresentInvention

[0066] In FIG. 1, the laser beam scanning mechanism of the presentinvention 1 is shown having a base portion 2 mounted (i.e., anchored) ona support structure 3 of an optical bench 4, and a laser beam deflectingportion 5 extending from the base portion, with a flexible gap portion 6disposed therebetween.

[0067] As shown, the laser beam deflecting portion 5 bears a lightdeflecting element 7 on its front surface and a thin permanent magnetelement 8 mounted on its rear surface. The light deflecting element 7can be realized in a number of different ways, namely: as a lightreflective element such as a mirror; as a light diffractive element suchas a reflection or transmission hologram (i.e., HOE); as a lightrefractive element such as a lens element; or as any other type ofoptical element capable of deflecting a laser beam along an optical pathas the laser beam deflecting portion 5 is oscillated about a fixed pivotpoint 9 defined at the interface between the anchored base portion andflexible gap portion of the scanning element. Light deflecting element 7and magnetic element 8 can be mounted to the scanning element using anadhesive, or other fastening technique (e.g., soldering) well known inthe art. In the illustrative embodiments disclosed herein, the laserbeam deflecting portion 5 is oscillated about its fixed pivot point byproducing a reversible magnetic force field 10 (e.g., of about 260Gauss) against the permanent magnet 8 (e.g., 20/1000th thick) mounted onthe rear surface of the laser beam deflecting portion.

[0068] In the illustrative embodiment, the positive polarity of thepermanent magnetic field is directed away from the light deflectingelement on the laser beam deflecting portion 5. The interaction ofmagnetic fields of opposite polarity produced by the permanentferrite-type magnet 8 and a stationary magnetic field producingelectromagnet 11 causes the laser beam deflecting portion 5 to oscillateabout its fixed pivot point 9 at both its natural resonant frequency ofoscillation, its harmonic modes of oscillation, as well as at thedriving or forcing frequency at which the polarity of the magnetic forcefield (produced by electromagnet 11) reverses in response to amplitudevariations in the electrical pulse train (driving the electromagneticcoil) which occur at a frequency controlled by an electronic signalgeneration circuit 12. In the illustrative embodiment, the angularexcursion x in the x-direction scanning plane is about ±15° away fromits non-deflected position. The function of the light deflecting element5 is to deflect a focused light beam 13 (produced by source 14) along ascanning path in response to oscillation of the light beam deflectingportion 5 about the fixed pivot point 9, defined above.

[0069] As shown in FIGS. 1, 1A and 1B, the scanning element of thepresent invention has a laminated construction, wherein: the anchoredbase portion 2 and the laser beam portion 5, each consist of a thinlayer of Kapton™ polyamide 16 sandwiched between a pair of thin layersof copper 17A and 17B, and 18A and 18B, respectively; and the flexiblegap portion 6 consisting of the thin layer of Kapton™ (polyamide)plastic material 18 and a thin layer of mechanically-damping filmmaterial, such as screenable silicone rubber (e.g., General Electric SLA74015-D1), having a suitable durometer measure, (e.g., Shore A40).Notably, the thin layer of polyamide in the anchored base portion 2, theflexible gap portion 5 and the laser beam deflecting portion 6 isrealized as a single unitary layer having a uniform thickness acrossthese individual portions of the scanning element. The copper layers onopposite sides of the anchored base portion, the flexible gap portionand the laser beam deflecting portion of the scanning element arediscrete elements of uniform thickness realized by precisely-controlledchemical-etching of the copper and polyamide layers during particularstages of the scanning element fabrication process described below.

[0070] Fabrication of the Scanning Element of the Present Invention

[0071] The preferred method of fabricating the flexible scanning elementof the present invention will be described with reference to. FIGS. 2,2A and 2B in the Drawings.

[0072] The first step of the fabrication method involves providing asheet of base material 20, in which sheets of thin copper foil material21A and 21B are laminated onto both front and back surfaces of a 12″×12″sheet of Kapton™ polyamide film material 22 using a epoxy adhesive.Suitable copper-laminated base material (“base material”) can beobtained from Techetch, Inc., of Plymouth, Mass. The cross-sectionalnature of this base material is shown in FIG. 2A.

[0073] Both sides of the 12″×12″ sheet of base material 20 arescreen-printed with a pattern of copper-protective ink (“photo-resist”).The copper-protective pattern is structured so that it covers thoseareas of the sheet where the copper elements associated with theanchorable base portion 2 and the laser beam deflecting portion 5 ofmany scanning elements are to be formed on the polyamide layer in aspatially-registered manner, as shown in FIGS. 2 and 2B. Those areas notcovered by the copper-protective pattern (i.e., where the gap portionsof the scanning elements are to be formed and scanning element mountinghole 25) are susceptible to the copper-etchant to be used in asubsequent etching stage. After the copper-protective pattern isprinted, the sheet is exposed to the copper-etchant by dipping the sheetin a reservoir of the same. Thereafter, the chemically-etched sheet,having etched copper surfaces 23A and 23B, is rinsed in a conventionalmanner. At this stage of the fabrication process, the copper elementsassociated with the anchorable base portion and the laser beam portionof 400 scanning elements are formed on 12″×12″ sheet in aspatially-registered manner; also, the gap portions of the scanningelements made from polyamide material are also formed betweencorresponding base and laser beam deflecting portions.

[0074] The next stage of the fabrication process involvesscreen-printing a pattern of polyamide-protective ink on thechemically-etched sheet. The polyamide-protective pattern is structuredso that it covers those areas of the sheet where the polyamide gapportions 6 have been previously formed, as well as very thin strips orstring-like elements (e.g., called “stringers”) between the copperelements associated with the anchorable base portion and the laser beamportion of neighboring scanning elements. Those areas of exposedpolyamide not covered by the polyamide-protective pattern describedabove (e.g., scanning element mounting hole 25) are susceptible to thepolyamide-sensitive etchant that is to be used in a subsequent etchingstage. After the polyamide-protective pattern is printed, the sheet isexposed to the polyamide-etchant by dipping the partially-etched sheetin a reservoir of the same. Thereafter, the etched sheet is rinsed in aconventional manner. At this stage of the fabrication process, thepolyamide elements associated with the gap portion of the 400 scanningelements are formed on 12″×12″ sheet, along with the copper elementsassociated with the base portions and laser beam deflecting portionsthereof. Each scanning element is suspended with respect to itsneighboring scanning element by way of the formed “stringers” 24 whichcan easily be broken by gently pulling a fabricated scanning elementfrom the nested matrix of scanning elements formed in the etchedcopper-cladded sheet described above.

[0075] While suspended within the nested matrix, a thin layer of GEsilicone (Durometer of Share A 40) of about 0.01 inch thick is screenedonto a single surface of the gap region of each scanning element. Thefunction of this silicone film layer is to provide mechanical dampingmechanism to the resonant scanning element being fabricated.

[0076] Once fabricated in the manner described above, the permanent(ferrite) magnets 8 and light deflecting (mirror) elements 7 can beattached to the laser beam deflecting portions of the etched scanningelements using CNC-based robotic machinery well known in the art. Inaddition, the completely fabricated scanning elements can then bemounted to their optical benches (or mounting brackets) using CNC-basedmachinery well known in the art.

[0077] Notably, while the above-described process involved treatingsingle sheets of base material, it is understood that alternativeembodiments of the present invention, a roll of base material can beused (instead of sheets) and treated using a continuous version of theabove-described fabrication process.

[0078] Tuning the scanning element described above is relatively easy.It has been determined that the natural resonant frequency ofoscillation of the light beam deflecting portion 5 is functionallyrelated to: the thickness of the layer of flexible material 16 (22); thephysical dimensions of the flexible gap portion 6; the total mass of thelaser beam deflecting portion, including the laser beam deflectingelement (e.g., mirror) 7 and the permanent magnet 8. For a givenpermanent magnet, mirror element and base material (e.g., double-sidedcopper-clad polyamide), the natural resonant frequency of the laser beamdeflecting portion about the fixed pivot point 9 can be preciselycontrolled by controlling the physical dimensions of the flexible gapregion 6 during the copper etching stage of the scanning elementfabrication process (i.e., printing the copper-protective andpolyamide-protective pattern). This technique enables tuning thescanning element over a fairly broad range of operation. For a greaterdegree of tuning, it might be desirable or necessary to use a differentbase material, in which the thickness of the polyamide layer is thicker(where a higher scanning frequency is required), or thinner (where alower scanning frequency is required).

[0079] While sophisticated mathematical models of the scanning elementcan be created to assist in the design process of the scanning elementhereof, it has been found that straight forward experimentation can beused to determine the gap dimensions for a desired natural operatingfrequency. As the forced frequency of operation is the “operatingfrequency” of the scanning mechanism, the designer will start with thedesired operating frequency (i.e., set by scanning speed requirements,bar code symbol resolution, signal processing limitations, etc.) andfigure out what the natural resonant frequency of the scanning elementmust be (e.g., at least 10% away from the forced frequency ofoperation). Knowing the approximate range of the natural resonantfrequency of the scanning element under design, the designer can thenexperiment (or model) in a straight forward manner to determine thephysical dimensions required to attain the desired natural frequency ofoscillation for a scanning element fabricated from a particular basematerial.

[0080] Using the above-described fabrication technique, scanningelements have been fabricated with natural resonant frequencies ofoperation within the range of about 50Hz to about 250Hz.

[0081] In the Table I below, the resonant frequencies are listed for anumber of different scanning elements (1) fabricated using base materialhaving a polyamide thickness of 0.001 inches, and 2.0 ounce double-sidedcopper cladding, and (2) having a laser beam deflecting portion(including a mirror and permanent magnet) with a total mass of about0.11 grams (i.e., where the ferrite magnet has a mass of 0.04 grams andmirror having mass of 0.03 grams). Double sided copper clad 2.0 ozPolyamide layer thickness 0.001 inch Mass of Ferrite Magnet 0.04 gramsMass of Mirror Element 0.03 grams Total Mass of Light Beam 0.11 gramsDeflecting Portion Gap Region Height 0.160 inch Thickness of Silicon0.01 inch Damping Film Layer Applied over one side of Gap RegionDurometer of Silicone Shore A 40 Damping Film Layer RESONANT FREQUENCY(Hz) GAP REGION WIDTH (Inch) 25   .065 26.5 .060 28.0 .055 29.5 .05031.0 .045 32.5 .040 34.0 .035 35.5 .030 37.0 .025 38.5 .020 40.0 .015

[0082] In the Table II below, the resonant frequencies are listed for anumber of different scanning elements (1) fabricated using base materialhaving a polyamide thickness of 0.003 inches, and 2.0 ounce double-sidedcopper cladding, and (2) having a laser beam deflecting portion(including a mirror and permanent magnet) with a total mass of about0.11 grams (i.e., where the ferrite magnet has a mass of 0.04 grams andmirror having mass of 0.03 grams). Double sided copper clad 2.0 ozPolyamide layer thickness 0.003 inch Mass of Ferrite Magnet 0.04 gramsMass of Mirror Element 0.03 grams Total Mass of Light Beam 0.11 gramsDeflecting Portion Gap Region Height 0.160 inch Thickness of Silicon0.01 inch Damping Film Layer Applied over one side of Gap RegionDurometer of Silicone Share A 40 Damping Film Layer RESONANT FREQUENCY(Hz) GAP REGION WIDTH (Inch) 75 .065 79.5 .060 84 .055 88.5 .050 93 .04597.5 .040 102 .035 106.5 .030 111 .025 115.5 .020 120 .015 124.5 .010

[0083] Laser Beam Scanning Module of the First Illustrative Embodiment

[0084] In FIG. 3, a laser beam scanning mechanism of the firstillustrative embodiment is shown realized on an optical bench 26 ofplanar dimensions. Magnetic-field producing coil (i.e., electromagneticcoil) 11 is supported upon a first projection (e.g., bracket) 27 whichextends from the optical bench. The scanning element of the presentinvention described above is mounted upon a second projection 28 whichextends from the optical bench. The permanent magnet 8 is placed inclose proximity with the magnetic-field producing coil 11, as shown inFIG. 3. A visible laser diode (VLD) 29 is mounted adjacent the scanningelement (by way of bracket 30) so that its output laser beam 31 isdirected towards a beam folding mirror 32, supported from a thirdprojection (bracket) 33 extending from the optical bench. The laser beamreflected off the beam folding mirror 32 is directed towards the laserbeam deflecting portion 5 of the scanning element and reflects outwardlyalong the projection axis 34 of the scanning module. The scanningelement is forced into oscillatory motion by driving the electromagneticcoil 11 with a voltage signal having a frequency substantially off theresonant frequency of the scanning element (e.g., by at least 10%).

[0085] In the preferred embodiment, the electromagnetic coil 11 isdriven in a push-pull mode, in which the magnetic polarity of the coilreverses periodically at rate determined by the amplitude variation ofthe voltage signal applied across the terminals 34 of theelectromagnetic coil 11. A suitable voltage waveform for driving theelectromagnetic coil 11 in the laser beam scanning mechanism of FIG. 3can be generated by the electronic circuit 12 shown in FIG. 3A. Asshown, electronic circuit 12 comprises: a clock generator 36 forproducing a clock signal having a frequency f₁ determined by an externalRC network, comprising resistor R and capacitor C, where the clockfrequency thereof f₁ is determined by the expression f₁ {fraction(1/2.07)} RC; a divider circuit 37 for dividing clock frequency f₁ by afactor of twenty (20) to produce f₂=f₁/20; and a conventional push-pullcurrent drive integrated circuit (IC) chip 38 connected tomagnetic-field producing coil 11 in an electrically-floating manner(i.e., not connected to electrical ground) as shown in FIG. 3A. The RCnetwork is used to set the frequency of the drive current in coil 11,which sets the scan rate (e.g., sweeps or scan lines per second) of thescanning mechanism.

[0086] In the illustrative embodiment, where for example the resonantfrequency of the scanning element is about 34 Hz, the controlledfrequency of the laser beam scanning mechanism should be set at about 28Hz or 41 Hz (e.g., ±7 Hz about the resonant frequency) which, in turn,determines the scan rate of the laser scanning module to be 56 or 82scan lines seconds, respectively. The controlled frequency of thescanning mechanism is set by adjusting the frequency of the drivecurrent signal in coil 11. The scanning mechanism of the presentinvention can be designed to provide scan rates higher than 250 scanlines per second (e.g., by using a thicker polyamide layer and/ornarrowing the gap region of the scanning element.

[0087] Laser Beam Scanning Module of the Second Illustrative Embodiment

[0088] In FIGS. 4 and 4A, a second illustrative embodiment of aminiature laser beam scanning module 40 is shown realized using anultra-compact plastic housing 41, in which the electromagnetic coil 11and the laser beam scanning mechanism of FIG. 1 are mounted. As shown,plastic housing 41 comprises a bottom plate 41A, side walls 41B and 41Cextending from the base plate, and a surface 41D for mounting theanchorable base portion 2 of the scanning element hereof thereto.Housing 41 also is provided with a recess 42 in side wall 41C, withinwhich the magnetic-field producing coil 11 can be mounted in a press-fitmanner. When assembled, the scanning element extends towards the centralaxis of the magnetic-field producing coil 11 so that the permanentmagnet 8 is closely positioned adjacent one end of the coil, while theother end thereof, mounted on a support post 43 in recess 42, is mountedthereto. The terminals of the magnetic-field producing coil can bepassed through small holes drilled in side wall 41C. Bottom plate 41Ahas a pair of holes 45A and 45B formed therein for receiving the ends ofposts 46A and 46B which extend from cover plate 47. A projection 48 oncover plate 47 snaps into hole 49 in the top surface 41E of the sidewall 41B, while mounting posts 46A and 46B snap within holes 45A and45B, respectively. When the cover 47 is assembled with the plastichousing 41, the posts 46A and 46B straddle the flexible gap portion 6 ofthe scanning element and function to delimit the maximum angular swingthereof if and when the scanning mechanism is subjected to excessiveexternal forces as might be experienced when dropped to the ground. Insuch an assembled configuration, the laser beam scanning module has ascanning aperture 50, through which the laser beam can be swept alongeither a 1-D or 2-D scanning pattern. Preferably, all of the componentsof the housing described above are fabricated using injection moldingtechnology well known in the art.

[0089] As shown, the bottom plate of the module includes a set of bottomprojections 51A, 51B, 51C and 51D which can be used to mount the plastichousing with respect to a primary optical bench or other surface withina host system incorporating the same.

[0090] Laser Beam Scanning Module of the Third Illustrative Embodiment

[0091] A third illustrative embodiment of the present invention is shownin FIG. 5. In this illustrative embodiment, a pair of miniature laserbeam scanning modules 40A and 40B, described in detail above, andvisible laser diode (VLD) 29 are configured onto an optical bench 53 inorder to form an ultra-compact laser beam scanning device capable ofselectively producing a 1-D or 2-D (raster-type) laser scanning patternunder the control of electronic circuitry 54. The optical bench 53 canbe mounted within a hand-held scanner housing, a countertop housing, orany other housing geometrically adapted to a particular application. Asshown in FIG. 5, the optical bench 53 allows the modules 40A and 40B tobe mounted relative to each other so that the scanning aperture 50A ofthe first module is orientable along the x-axis of the scanning field,while the scanning aperture 50B of second module is orientable along they-axis thereof. In some applications, it might be desired to provide theis optical bench with beam folding mirrors in order to fold the producedscanning beam in a particular manner. In the illustrative embodiment,the x-direction scanning element undergoes a maximum angular excursionof about ±15° about its non-deflected position, whereas the maximumangular excursion for the y-direction scanning element is about ±1.5°about the non-deflected position thereof.

[0092] As shown in FIG. 6, the function of electronic circuitry 54 is toproduce drive signals for synchronously driving the laser scanningmodules 40A and 40B so that 1-D or 2-D scanning patterns are producedunder electronic control. This circuitry can be realized on a smallprinted circuit (PC) board attached to the optical bench 53 or elsewherewithin the host system housing.

[0093] In the illustrative embodiment, a push-pull driver IC 56 is usedto produce a current drive signal for the x-axis magnetic-fieldproducing coil 11A. The clock frequency of the clock signal 57 producedfrom push-pull drive circuit 56 is set by an externalresistor/capacitator network 58 (R1 and C1) connected to a 5 Volt powersupply in a manner well known in the art. The output clock frequencyshown in FIG. 7A serves as a base or reference signal for the operationof circuit 54. As shown, the output clock signal is provided as input toa synchronous (4-bit) binary counter 60 which produces a plurality ofoutput clock signals having different clock rates (e.g., 2, 4, 8, etc.)In turn, these output clock signals, along with a DC signal, areprovided as input signals to a multi-channel data selector/multiplexer61 (e.g., whose control or gating signals are provided by the systemcontroller 62 of the host system (e.g., hand-held bar code symbolreader, countertop scanner, vending machine, etc.) 63. The single outputof the data-selector/multiplexer 61 is provided as input to an inverter64 which is used to drive a transistor (Q1) 65 through a resistor R2connected to the base thereof, with the transistor emitter connected toelectrical ground. In turn, the collector and emitter junction of thetransistor 65 are connected in series with a current limiting resistorR3, a y-axis magnetic-field producing coil 11B and the 5 Volt powersupply.

[0094] In the illustrative embodiment, the system controller 62 isoperably connected to the symbol decoding module 66 of the host system63. Typically, the symbol decoding module is a programmed microprocessorcapable of decoding 1-D and 2-D bar code symbols usingautodiscrimination techniques and the like. An exemplary systemarchitecture for the host system 63 is described in great detail in U.S.Pat. Nos. 5,260,553, 5,340,971, and 5,557,093, incorporated herein byreference. During decode processing, the symbol decoding module 64carries out one more 2-D decoding algorithms, each embodying“Scan-Pattern Optimization Control Logic”. According to such controllogic, if during the 2-D decoding process, a bar code symbol is decoded,then the decoding module proceeds to determine how many rows of scandata are contained in the 2-D bar code symbol. This is achieved byreading the “row” indication field in the decoded line of scan data anddetermining the number of rows within the scanned 2-D bar code symbol.When this information is recovered by the symbol decoding module, it isthen provided to the system controller 62. In turn, the systemcontroller uses this information to generate a control signal for thedata-selector/multiplexer 61. The control signal selects a signal (atthe multiplexer's input) which drives the y-axis magnetic-fieldproducing coil 11B in a manner such that the 2-D bar code symbol isoptimally scanned.

[0095] For example, if the symbol decoding module detects a 1-D bar codesymbol, then the system controller will automatically produce a controlsignal that causes the multiplexer 61 to select a DC voltage, therebycausing the y-axis magnetic-field producing coil 11B to remain pinneddown, and prevented from deflecting the laser beam along the y-axis ofthe scanning beam.

[0096] If the symbol decoding module 64 detects a “Post-Net” type 2-Dbar code symbol, then the system controller will produce a controlsignal that causes the multiplexer to select a clock signal that causesthe y-axis magnetic-field producing coil 11B to produce a 2-line rasterscanning pattern. If the symbol decoding module detects a “PDF orequivalent” type 2-D bar code symbol, then the symbol decoder determineshow many rows of data are contained in the PDF code symbol. Based on thenumber of rows of data contained within the scanned 2-D bar code symbol,the system controller will dynamically generate a control signal thatcauses the y-axis magnetic-field producing coil to produce an optimalnumber of scan lines in the scanning pattern, related to the number ofrows of data contained within the scanned code symbol.

[0097] If the symbol decoding module determines that the PDF symbol hasbetween 2-4 rows of data, then the system controller will produce acontrol signal that causes the multiplexer to select a clock signal thatcauses the y-axis magnetic-field producing coil 11B to produce a 2-lineraster scanning pattern. If the symbol decoding module determines thatthe PDF symbol has between 5-10 rows of data, then the system controllerwill produce a control signal that causes the multiplexer to select aclock signal that causes the y-axis magnetic-field producing coil 11B toproduce a 4-line raster scanning pattern. If the symbol decoding moduledetermines that the PDF symbol has 11 or more rows of data, then thesystem controller will produce a control signal that causes themultiplexer to select a clock signal that causes the y-axismagnetic-field producing coil 11B to produce an 8-line raster scanningpattern.

[0098] During operation of the electronic drive circuitry of FIG. 6, thepush-pull drive IC 56 produces a clock signal 57 as shown in FIG. 7A.Based on this clock signal, a current drive signal shown in FIG. 7B isproduced for driving the x-axis magnetic-field producing coil. As theoperation of the x-axis magnetic-field producing coil 11A is reversible(i.e., its magnetic polarity reverses in response to current directionreversal therethrough), the current direction is referenced about a zeromilliampere (0.0 mA) value. Each time the current drive signal changesdirection through windings of the x-axis magnetic-field producing coil11A, so too does the magnetic polarity of the magnetic-field produced althereby and thus the direction of deflection of the scanning elementalong the x-axis.

[0099] To prevent deflection of the laser beam along the y-axis, andthus create a 1-D scanning pattern, the system controller will select aDC voltage at multiplexer 61. The selected DC voltage will forward biasthe current drive transistor 65 so that a constant current flows throughy-axis magnetic-field producing coil 11B, pinning the scanning elementof the y-axis scanning module and preventing deflection of the laserbeam along the y-axis in response to base clock signal 57 shown in FIG.7A.

[0100] To produce a 2-D laser scanning pattern, the system controllerwill select one of the voltage signals shown in FIGS. 7C through 7E fordriving current drive transistor 65 connected to the y-axismagnetic-field producing coil 11B. As illustrated in FIG. 6, wheneverthe amplitude of the selected voltage signal is below a predeterminedthreshold (e.g., 0 Volts), then invertor 64 will produce an outputvoltage which forward biases the current drive transistor 65, causingelectrical current to flow through the y-axis magnetic-field producingcoil and a magnetic field produced in response thereto. Under suchconditions, the y-axis magnetic-field producing coil 11B deflects thelaser beam along the y-axis. When the amplitude of the selected voltagesignal rises above the threshold level, the output of the invertor 64decreases so that the current drive transistor 65 is no longerforward-biased. This condition causes current flow through the y-axismagnetic-field producing coil to cease and the magnetic field therefromto collapse, thereby allowing the scanning element to deflect the laserbeam in the opposite direction.

[0101] When the selected control voltage changes polarity, the y-axiscoil is once again actively driven and the scanning element thereofdeflected, causing the horizontally deflected laser beam to be deflectedin along the y-axis. The number of horizontal scan lines produced eachtime the laser beam is deflected along the y-axis depends on how slowlythe amplitude of the selected control voltage (from the multiplexer)changes as the x-axis magnetic-field producing coil deflects the laserbeam along the x-axis each time the current drive signal shown in FIG.7B undergoes a signal level transition from high to low.

[0102] Notably, the selected control voltage shown in FIG. 7E allowseight horizontal scan lines to be created along the x-axis before itundergoes its signal level transition, which in effect triggers therepositioning of the laser beam along the start position of the y-axis.The finish position along the y-axis depends on the time that theselected control voltage remains below the threshold voltage, as well asother factors (e.g., scanning aperture of the modules, host scanner,etc.).

[0103] Using the above-described principles of the present invention,clearly it is possible to produce 2-D raster scanning patterns having anumber of horizontal scan lines that are optimally matched to the numberof rows of data within virtually any 2-D bar code symbol being scanned.

[0104] In an alternative embodiment of the present invention, it ispossible for the symbol decoding module 64 to collect informationregarding (i) the number of rows in a scanned 2-D bar code symbol and(ii) the length of the data rows. The system controller 62 can then usethe row number information to set the number of horizontal scan lines tobe produced in the scanning pattern, while the row length informationcan be used to set the length of the scan lines by limiting theamplitude of electrical current through the x-axis magnetic-fieldproducing coil 11A.

[0105] As shown in FIG. 6, such control can be achieved by controller 62sending a control signal 66 to push-pull drive circuit 56, or an activeelement 67 provided in series with electromagnetic coil 11A for thepurpose of actively controlling the electrical current flowingtherethrough.

[0106] In another embodiment of the present invention, it is possiblefor the symbol decoding module to collect information regarding (i) thenumber of rows in a scanned 2-D bar code symbol, (ii) the length of thedata rows, and (iii) count data representative of the distance of thesymbol in the scanning volume. The system controller can then use therow number information to set the number of horizontal scan lines to beproduced in the scanning pattern, and the row length information andcount data to set the length of the horizontal scan lines (by limitingthe amplitude of electrical current through the x-axis magnetic-fieldproducing coil 11A by current control signal 66). By controlling suchscanning parameters, the system controller of the host system canachieve real-time control over the aspect-ratio of the 2-D scanningpattern.

[0107] An advantage of such system functionalities will be to improvethe visibility of the scanned laser beam, and optimize data collectionoperations as the laser beam will only be scanned over regions in spacewhere symbol data is likely present.

[0108] In FIGS. 8A1 and 8A2, the laser scanning module of the presentinvention is shown being operated in its 1-D Scanning Mode. In thismode, a scan pattern is produced having a single horizontal scan line.In FIGS. 8B through 8D, the laser scanning module is shown beingoperated in different variations of its 2-D Scanning Mode, in which araster-type scanning pattern is produced. In each of these figures, adifferent raster scanning pattern is shown being produced with adifferent number of scan lines. Preferably, the particular number ofscan lines produced are automatically selected by the system controllerof the present invention, as described in great detail above.

[0109] Scanning mode selection can be realized in a number of differentways. One way would be to mount an external button on the housing of thebar code symbol reader into which the scanning module has beenintegrated. When this mode selection button is depressed, the readerautomatically enters a particular scanning mode. Alternatively, scanningmode selection can be achieved by way of reading a predetermined barcode symbol encoded to automatically induce a particular mode ofoperation. When a predetermined bar code symbol is read, the scanningmodule automatically enters the scanning mode represented by the scannedbar code symbol.

[0110] Illustrative Embodiments of Bar Code Scanning Systems Embodyingthe laser Scanning Module of the Present Invention

[0111] In general, the laser scanning modules of the present inventioncan be embodied within diverse types of bar code driven systems,including hand-held bar code symbol readers, body-wearable bar codesymbol readers, fixed counter scanners, transaction terminals,reverse-vending machines, CD-juke boxes, etc. In FIGS. 9 through 11, afew illustrative examples are shown where such laser scanning modulescan be embodied. Such examples are not intended to limit the scope ofthe present invention, but simply illustrate several of the manyenvironments that the laser scanning modules of the present inventionmight be embedded.

[0112] In FIGS. 9 and 9A, the laser scanning module of FIG. 5 is shownembodied within a hand-supportable bar code symbol reader 70 of the typedescribed in U.S. Pat. Nos. 5,260,553 and 5,340,971, incorporated hereinby reference. In FIG. 9, the scanner is shown being used in its hands-onmode of operation. In FIG. 9A, the scanner is shown being used in itshands-free mode of operation, where it is supported within a stand 71.In either of these modes of operation, 1-D or 2-D laser scanningpatterns 73 can be automatically produced from the bar code symbolreader in the manner described hereinabove.

[0113] In FIG. 10, the laser scanning module of FIG. 5 is shown embodiedwithin a hand-held bar code symbol driven Internet-based access terminal75. As shown, the terminal 75 is shown connected to an ISP 76 by way ofa radio-base station 77 and wireless link 78 The hand-held InternetAccess Terminal 75 has an integrated GUI-based web browser program,display panel 79, touch-screen type keypad 80, and programmed bar codesymbol scanner 81 incorporating the laser scanning module of FIG. 5. Thefunction of bar code symbol scanner 81 can be multi-fold: namely: it maybe used to read a bar code symbol 82 that is encoded with the URL of atransaction-enabling Web page to be accessed from a web (http) server 83by the Internet-based Transaction-Enabling System, and produce symbolcharacter data representative thereof; it may be used to read UPC-typebar code symbols in order to access a database connected to the Internet85 by way of a common gateway interface (CGI); or it may be simply usedto read other types of bar code symbols that identify a product orarticle in a conventional manner.

[0114] In the illustrative embodiment, the Internet Access Terminal 75is realized as a transportable computer, such as the Newton® Model 2000Messagepad from Apple Computer, Inc. of Cupertino, Calif. This device isprovided with NetHopper™ brand Internet Access Software from whichsupports the TCP/IP networking protocol within the Newton MessagePadoperating system. The Newton Messagepad is also equipped with a MotorolaPCMICA-based modem card 86 having a RF transceiver for establishing awireless digital communication link with either (i) a cellular basestation, or (ii) one or more satellite-base stations connected to theInternet by way of ISP 76 in a manner well known in the globalinformation networking art.

[0115] As shown, the entire Newton MessagePad, ScanQuest® laser scanningmodule 81 and auxiliary battery supply (not shown) are completely housedwithin a rubberized shock-proof housing 87, in order to provide ahand-supportable unitary device. Once the object (e.g., transactioncard) 88 is detected by the object detection field 89, a laser beam 90is automatically projected and swept across the bar code symbol thereon.

[0116] In the above-illustrative embodiments, the bar code symbolreading device has been either supported within the hand of theoperator, upon a countertop surface or the like. It is contemplated,however, that the laser scanning module of the present invention can beembodied within a body-wearable bar code symbol reader designed to beworn on the body of an operator as illustrated in FIG. 11. As shown, thebody-wearable Internet-based system 91 comprises: a bar code symbolscanning unit 92 designed to be worn on the back of the hand, and withinwhich the 1D/2D laser scanning module of the present invention isintegrated; and a remote unit 93 (i.e., body-wearable RF-based Internetaccess terminal) designed to be worn about the forearm or foreleg of theoperator by fastening thereto using flexible straps or like fasteningtechnology.

[0117] In the illustrative embodiment, hand-mounted scanning unit 92comprises: a light transmission window 94 for exit and entry of lightused to scan bar code symbols; a glove 95 worn by the operator forreleasably mounting the housing 96 to the back of his or her hand; and alaser scanning bar code symbol reader 97, as described hereinabove withrespect to the other illustrative embodiments of the present invention.

[0118] In the illustrative embodiment, the remote unit 93 comprises: anLCD touch-screen type panel 97; an audio-speaker 98; a RISC-basedmicrocomputing system or platform 99 for supporting various computingfunctions including, for example, TCP/IP, HTTP, and other Internetprotocols (e.g., E-mail, FTP, etc.) associated with the use of anInternet browser or communicator program (e.g., Netscape Navigator orCommunicator, or MicroSoft Explorer programs) provided by the remoteunit; a telecommunication modem 100 interfaced with the microcomputingsystem; an RF transceiver 101 (e.g., employing DFSK or spread-spectrummodulation techniques) also interfaced with the telecommunication modemfor supporting a 2-way telecommunication protocol (e.g., PPP) known inthe art, between the microcomputing system and a remote transceiver 102(described hereinabove) which is interfaced with ISP 103 connected tothe Internet; a (rechargeable) battery power supply 104 aboard theremote housing, for providing electrical power to the components thereinas well as to the bar code symbol reader 97; and a flexible cable 105,for supporting communication between the bar code symbol reader and themicrocomputing platform, and electrical power transfer from the powersupply to the bar code symbol reader. Notably, the remote unit 93 willembody one of the Internet access methods described hereinabove. Themethod used by remote unit 93 (i.e., Internet access terminal) willdepend on the information that is encoded within the bar code symbolscanned by the bar code symbol reader thereof. Preferably, the remoteunit is worn on the forearm of the operator so that the touch-type LCDpanel 97 integrated therewith can be easily viewed during use of thebody-wearable system of the present invention. Thus, for example, whenan URL-encoded bar code symbol is read by the hand-mounted (orfinger-mounted) bar code symbol reader 92, the transaction-enabling Webpage associated with the scanned bar code symbol and displayed on theLCD panel can be easily viewed by and interacted with by the operator.Also, in response to reading an URL-encoded bar code symbol (i.e.,transaction enabled thereby), the operator may be required to manuallyenter information to the Web page being displayed, using thetouch-screen display panel 97 and pen-computing software, well known inthe art.

[0119] Having described the illustrative embodiments of the presentinvention, several modifications readily come to mind.

[0120] For example, while the illustrative embodiments have disclosedthe use of base sheet material comprising copper laminated onto Kapton™plastic material during the fabrication of the scanning element hereof,it is understood that other types of resilient plastic materials,including Mylar™ plastic material, can be used to manufacture thescanning element with suitable results.

[0121] Also, in some applications, it might be desirable to configureseveral 1D/2D laser beam scanning modules hereof in relation with eachother in order to generate various types of omnidirectional scanningpatterns.

[0122] Also, the VLD and its associated beam shaping optics may beintegrated within any of the module housings disclosed herein in orderto produce an miniature laser scanner capable of producing ID and 2Dscanning patterns under electronic control. Such laser scanners can beintegrated within various types of systems using bar code symbols todrive or direct host system operation.

[0123] It is understood that the laser scanning modules of theillustrative embodiments may be modified in a variety of ways which willbecome readily apparent to those skilled in the art of having thebenefit of the novel teachings disclosed herein. All such modificationsand variations of the illustrative embodiments thereof shall be deemedto be within the scope and spirit of the present invention as defined bythe claims to Invention appended hereto.

What is claimed:
 1. Apparatus for deflecting a light beam, comprising:an optical bench; a scanning element of unitary construction having abase portion, a light beam deflecting portion, and a gap region disposedtherebetween, said base portion being anchored with respect to saidoptical bench so as to permit said light beam deflecting portion topivot about a fixed pivot point defining between said base portion bysaid gap region, said light beam deflecting portion having a naturalresonant frequency of oscillation about said fixed pivot point and beingmechanically-damped at said gap region; a permanent magnet mounted onsaid light beam deflecting portion; a light beam deflecting elementmounted on said light beam deflecting portion, for deflecting a lightbeam falling incident upon said light beam deflecting element; amagnetic-field producing coil having a pair of input terminals, anddisposed adjacent said permanent magnet, for producing a magnetic forcefield of reversible polarity in the vicinity of said permanent magnet inresponse to an electrical current signal flowing through saidmagnetic-field producing coil, at an aplitude which varies at acontrollable frequency; an electrical circuit operably connected to saidpair of input terminals, and producing an electrical voltage signalwhich causes said electrical current signal to flow through saidmagnetic-field producing coil and produce in the vicinity of saidmagnetic-field, said magnetic force field having a polarity which variesin accordance with the amplitude and frequency of said electricalcurrent flowing through said magnetic-field producing coil, whereby saidmagnetic force field interacts with said permanent magnetic and forcessaid light beam deflecting portion to oscillate about said fixed pivotpoint at a controlled frequency of oscillation that is substantiallydifferent from said natural resonant frequency of oscillation of saidlight beam deflecting portion, so that a light beam incident upon saidlight beam deflecting element is periodically deflected as said lightbeam deflecting portion oscillates about said fixed pivot point at saidforced frequency of oscillation, creating a one-dimensional scanningpattern for scanning bar code symbols.
 2. The apparatus of claim 1,which further comprises a light beam source for producing a light beamfor directing incident upon the surface of said light beam deflectingportion.
 3. The apparatus of claim 2, wherein said controlled frequencyof oscillation is different in magnitude than said natural resonantfrequency of oscillation by at least 10% of said natural resonantfrequenccy.
 4. The apparatus of claim 1, wherein said light beamdeflecting portion, said small gap portion and said base portion eachcomprise a layer of flexible material, and said light beam deflectingportion and said base portion each include a pair of metal elementsmounted in registration on said layer of flexible material.
 5. Theapparatus of claim 4, wherein said natural resonant frequency ofoscillation of said light beam deflecting portion is related to thethickness of said layer of flexible material and the dimensions of saidsmall gap portion.
 6. The apparatus of claim 1, wherein said light beamdeflecting element comprises a light reflective element mounted onto thefront surface of said light beam deflecting portion.
 7. The apparatus ofclaim 1, wherein said light beam deflecting element comprises a lightrefractive element mounted onto the front surface of said light beamdeflecting portion.
 8. The apparatus of claim 1, wherein said light beamdeflecting element comprises a light diffractive element mounted ontothe front surface of said light beam deflecting portion.
 9. Theapparatus of claim 1, wherein said permanent magnet is mounted on saidrear surface of said light beam deflecting portion, and said light beamdeflecting element is mounted on said front surface of said light beamdeflecting portion.
 10. The apparatus of claim 1, wherein said opticalbench comprises a module having a first wall structure in which saidmagnetic-field producing coil is mounted, and a second wall structure towhich said base portion is mounted.
 11. The apparatus of claim 10,wherein said module further comprises a pair of stops disposed onopposite sides of said small gap portion, to restrict the angularrotation of said scanning element about said fixed pivot point.
 12. Theapparatus of claim 10, wherein said module comprises a scanning aperturethrough which said light beam is permitted to be swept as said as saidlight beam deflecting portion oscillates about said fixed pivot point atsaid forced frequency of oscillation.
 13. The apparatus of claim 1,wherein said electrical circuit comprises means for setting saidcontrolled frequency.
 14. The apparatus of claim 1, which furthercomprises a light source for producing said light beam directed incidenton said light beam deflecting element.
 15. The apparatus of claim 14,wherein said light source comprises a visible laser diode.
 16. A barcode symbol reading system, comprising: said apparatus of claim 1, forproducing a one-dimensional scanning pattern for scanning a bar codesymbol on an object; light collecting means for collecting lightreflected of said scanned bar code symbol; light detecting means fordetecting said collected light and producing scan data indicative of theintensity of said detected light; and scan data processing means fordecode processing said scan data in order to produce symbol characterdata representative of said scanned bar code symbol.
 17. A system forproducing a 2-D raster scanning pattern, comprising: a light source forproducing a light beam having cross-sectional characteristics suitablefor scanning a 2-D bar code symbol; a first light beam scanningmechanism, responsive to a first control signal, for scanning said lightbeam along a first reference direction using a first scanning elementhaving a first natural resonant frequency of oscillation; a second lightbeam scanning mechanism, responsive to a second control signal, forscanning said light beam along a second reference direction orthogonalto said first reference direction using a second scanning element havinga second natural resonant frequency of oscillation; scanning mechanismcontrol means for synchronously controlling said first scanning elementto oscillate substantially away from said first natural resonantfrequency and said second scanning element to oscillate at a frequenccysubstantially different than said second natural resonant frequency, sothat a 2-D raster scanning pattern is generated from said system. 18.The system of claim 17, which further comprises: light collecting meansfor collecting light reflected off a bar code symbol scanned by said 2-Draster scanning pattern; light detecting means for detecting saidcollected light and producing scan data indicative of the intensity ofsaid detected light; and scan data processing means for decodeprocessing said scan data in order to produce symbol character datarepresentative of said scanned bar code symbol.
 19. A method offabricating a plurality of scanning elements of unitary construction,each having a anchorable base portion and a light beam reflectingportion interconnected by way of a flexible gap portion, said methodcomprising the sequence of steps of: (a) supplying a quantity of basematerial comprising a flexible plastic layer interposed between a pairof metal layers laminated to both sides thereof; (b) selectively etchingsaid metal layers so as to form metal patterns corresponding to portionsof said anchorable base portions and said light beam deflecting portion,and plastic patterns corresponding to portions of said flexible gapportions; and (c) selectively etching said flexible plastic material soas to form a plurality of said scanning elements suspended together byfine string-like elements.
 20. The method of claim 19, which furthercomprises after step (c) breaking said string-like elements so as tofree said scanning element for installation with laser scanningmechanism.
 21. The method claim 19 wherein said step (b) compriseschemically etching said metal layers.
 22. The method of claim 19, whichfurther comprises mounting a light reflecting element onto the frontsurface of each said light deflecting portion, and permanent magnetelement onto the rear surface of each said light deflecting portion.